A rechargeable secondary battery is mounted to a portable electronic device such as a mobile communication terminal and PDA. To charge the secondary battery, a separate charging device for supplying an electric energy to the battery of a portable electronic device using an AC line power is required. Generally, separate contact terminals are respectively provided to outsides of the charging device and the battery so that the charging device and the battery may be electrically connected with each other by connecting both contact terminals.
However, if a contact terminal is exposed out as mentioned above, an appearance is deteriorated and the contact terminal is contaminated due to external impurities to easily cause an inferior contact status. In addition, if the battery is short-circuited or exposed to moisture due to the carelessness of a user, the charged energy may be easily lost.
In order to solve the problem of the contact-type charging method, a wireless charging system that allows charging in a contactless manner between the charging device and the battery has been proposed.
Korean Laid-open Publication No. 2002-57468, Korean Laid-open Publication No. 2002-57469, Korean Patent Registration No. 363,439, Korean Patent Registration No. 428,713, Korean Laid-open Publication No. 2002-35242, Korean Utility Model Registration No. 217,303, GB 2,314,470, and US Publication Serial No. 2003/0,210,106 disclose a contactless charger system that charges a battery without a contact terminal using inductive coupling between a primary coil of a charging body and a secondary coil of a battery pack.
In addition, Korean Laid-open Publication No. 2004-87037 discloses a contactless chargeable battery pack including a control circuit for accumulating information such as a use time and a charging capacity by measuring voltage and current of a battery, and then correcting a charging/discharging capacity of the battery based on the accumulated information. In particular, the control circuit further includes a compensating circuit for compensating a charging voltage and a battery temperature based on a charging voltage detected from the battery and a temperature of the battery detected by a temperature sensor.
However, Korean Laid-open Publication No. 2004-87037 does not disclose a power supplier for feeding back charging status information (e.g., charging current, charging voltage, etc.) and generating a charging power corresponding to the charging status information, or a contactless charger system using such a power supplier.